| /* |
| * Copyright (C) 2011 Google Inc. All rights reserved. |
| * |
| * Redistribution and use in source and binary forms, with or without |
| * modification, are permitted provided that the following conditions are |
| * met: |
| * |
| * * Redistributions of source code must retain the above copyright |
| * notice, this list of conditions and the following disclaimer. |
| * * Redistributions in binary form must reproduce the above |
| * copyright notice, this list of conditions and the following disclaimer |
| * in the documentation and/or other materials provided with the |
| * distribution. |
| * * Neither the name of Google Inc. nor the names of its |
| * contributors may be used to endorse or promote products derived from |
| * this software without specific prior written permission. |
| * |
| * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS |
| * "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT |
| * LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR |
| * A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT |
| * OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, |
| * SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT |
| * LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, |
| * DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY |
| * THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT |
| * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE |
| * OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE. |
| */ |
| |
| #include "third_party/blink/renderer/core/layout/flexible_box_algorithm.h" |
| |
| #include "third_party/blink/renderer/core/layout/layout_box.h" |
| #include "third_party/blink/renderer/core/layout/layout_flexible_box.h" |
| #include "third_party/blink/renderer/core/layout/min_max_size.h" |
| |
| namespace blink { |
| namespace { |
| |
| ItemPosition BoxAlignmentToItemPosition(EBoxAlignment alignment) { |
| switch (alignment) { |
| case EBoxAlignment::kBaseline: |
| return ItemPosition::kBaseline; |
| case EBoxAlignment::kCenter: |
| return ItemPosition::kCenter; |
| case EBoxAlignment::kStretch: |
| return ItemPosition::kStretch; |
| case EBoxAlignment::kStart: |
| return ItemPosition::kFlexStart; |
| case EBoxAlignment::kEnd: |
| return ItemPosition::kFlexEnd; |
| } |
| } |
| |
| ContentPosition BoxPackToContentPosition(EBoxPack box_pack) { |
| switch (box_pack) { |
| case EBoxPack::kCenter: |
| return ContentPosition::kCenter; |
| case EBoxPack::kJustify: |
| return ContentPosition::kFlexStart; |
| case EBoxPack::kStart: |
| return ContentPosition::kFlexStart; |
| case EBoxPack::kEnd: |
| return ContentPosition::kFlexEnd; |
| } |
| } |
| |
| ContentDistributionType BoxPackToContentDistribution(EBoxPack box_pack) { |
| return box_pack == EBoxPack::kJustify ? ContentDistributionType::kSpaceBetween |
| : ContentDistributionType::kDefault; |
| } |
| |
| } // namespace |
| |
| FlexItem::FlexItem(LayoutBox* box, |
| LayoutUnit flex_base_content_size, |
| MinMaxSize min_max_sizes, |
| base::Optional<MinMaxSize> min_max_cross_axis_sizes, |
| LayoutUnit main_axis_border_padding, |
| LayoutUnit main_axis_margin) |
| : algorithm(nullptr), |
| line_number(0), |
| box(box), |
| flex_base_content_size(flex_base_content_size), |
| min_max_sizes(min_max_sizes), |
| min_max_cross_sizes(min_max_cross_axis_sizes), |
| hypothetical_main_content_size( |
| min_max_sizes.ClampSizeToMinAndMax(flex_base_content_size)), |
| main_axis_border_padding(main_axis_border_padding), |
| main_axis_margin(main_axis_margin), |
| frozen(false), |
| ng_input_node(/* LayoutBox* */ nullptr) { |
| DCHECK(!box->IsOutOfFlowPositioned()); |
| DCHECK_GE(min_max_sizes.max_size, LayoutUnit()) |
| << "Use LayoutUnit::Max() for no max size"; |
| } |
| |
| bool FlexItem::MainAxisIsInlineAxis() const { |
| return algorithm->IsHorizontalFlow() == box->IsHorizontalWritingMode(); |
| } |
| |
| LayoutUnit FlexItem::FlowAwareMarginStart() const { |
| if (algorithm->IsHorizontalFlow()) { |
| return algorithm->IsLeftToRightFlow() ? box->MarginLeft() |
| : box->MarginRight(); |
| } |
| return algorithm->IsLeftToRightFlow() ? box->MarginTop() |
| : box->MarginBottom(); |
| } |
| |
| LayoutUnit FlexItem::FlowAwareMarginEnd() const { |
| if (algorithm->IsHorizontalFlow()) { |
| return algorithm->IsLeftToRightFlow() ? box->MarginRight() |
| : box->MarginLeft(); |
| } |
| return algorithm->IsLeftToRightFlow() ? box->MarginBottom() |
| : box->MarginTop(); |
| } |
| |
| LayoutUnit FlexItem::FlowAwareMarginBefore() const { |
| switch (algorithm->GetTransformedWritingMode()) { |
| case TransformedWritingMode::kTopToBottomWritingMode: |
| return box->MarginTop(); |
| case TransformedWritingMode::kBottomToTopWritingMode: |
| return box->MarginBottom(); |
| case TransformedWritingMode::kLeftToRightWritingMode: |
| return box->MarginLeft(); |
| case TransformedWritingMode::kRightToLeftWritingMode: |
| return box->MarginRight(); |
| } |
| NOTREACHED(); |
| return box->MarginTop(); |
| } |
| |
| LayoutUnit FlexItem::CrossAxisMarginExtent() const { |
| return algorithm->IsHorizontalFlow() ? box->MarginHeight() |
| : box->MarginWidth(); |
| } |
| |
| LayoutUnit FlexItem::MarginBoxAscent() const { |
| LayoutUnit ascent(box->FirstLineBoxBaseline()); |
| if (ascent == -1) |
| ascent = cross_axis_size; |
| return ascent + FlowAwareMarginBefore(); |
| } |
| |
| LayoutUnit FlexItem::AvailableAlignmentSpace() const { |
| LayoutUnit cross_extent = CrossAxisMarginExtent() + cross_axis_size; |
| return Line()->cross_axis_extent - cross_extent; |
| } |
| |
| bool FlexItem::HasAutoMarginsInCrossAxis() const { |
| if (algorithm->IsHorizontalFlow()) { |
| return box->StyleRef().MarginTop().IsAuto() || |
| box->StyleRef().MarginBottom().IsAuto(); |
| } |
| return box->StyleRef().MarginLeft().IsAuto() || |
| box->StyleRef().MarginRight().IsAuto(); |
| } |
| |
| ItemPosition FlexItem::Alignment() const { |
| return FlexLayoutAlgorithm::AlignmentForChild(*algorithm->Style(), |
| box->StyleRef()); |
| } |
| |
| void FlexItem::UpdateAutoMarginsInMainAxis(LayoutUnit auto_margin_offset) { |
| DCHECK_GE(auto_margin_offset, LayoutUnit()); |
| |
| if (algorithm->IsHorizontalFlow()) { |
| if (box->StyleRef().MarginLeft().IsAuto()) |
| box->SetMarginLeft(auto_margin_offset); |
| if (box->StyleRef().MarginRight().IsAuto()) |
| box->SetMarginRight(auto_margin_offset); |
| } else { |
| if (box->StyleRef().MarginTop().IsAuto()) |
| box->SetMarginTop(auto_margin_offset); |
| if (box->StyleRef().MarginBottom().IsAuto()) |
| box->SetMarginBottom(auto_margin_offset); |
| } |
| } |
| |
| bool FlexItem::UpdateAutoMarginsInCrossAxis( |
| LayoutUnit available_alignment_space) { |
| DCHECK(!box->IsOutOfFlowPositioned()); |
| DCHECK_GE(available_alignment_space, LayoutUnit()); |
| |
| bool is_horizontal = algorithm->IsHorizontalFlow(); |
| const Length& top_or_left = is_horizontal ? box->StyleRef().MarginTop() |
| : box->StyleRef().MarginLeft(); |
| const Length& bottom_or_right = is_horizontal ? box->StyleRef().MarginBottom() |
| : box->StyleRef().MarginRight(); |
| if (top_or_left.IsAuto() && bottom_or_right.IsAuto()) { |
| desired_location.Move(LayoutUnit(), available_alignment_space / 2); |
| if (is_horizontal) { |
| box->SetMarginTop(available_alignment_space / 2); |
| box->SetMarginBottom(available_alignment_space / 2); |
| } else { |
| box->SetMarginLeft(available_alignment_space / 2); |
| box->SetMarginRight(available_alignment_space / 2); |
| } |
| return true; |
| } |
| bool should_adjust_top_or_left = true; |
| if (algorithm->IsColumnFlow() && !box->StyleRef().IsLeftToRightDirection()) { |
| // For column flows, only make this adjustment if topOrLeft corresponds to |
| // the "before" margin, so that flipForRightToLeftColumn will do the right |
| // thing. |
| should_adjust_top_or_left = false; |
| } |
| if (!algorithm->IsColumnFlow() && |
| box->StyleRef().IsFlippedBlocksWritingMode()) { |
| // If we are a flipped writing mode, we need to adjust the opposite side. |
| // This is only needed for row flows because this only affects the |
| // block-direction axis. |
| should_adjust_top_or_left = false; |
| } |
| |
| if (top_or_left.IsAuto()) { |
| if (should_adjust_top_or_left) |
| desired_location.Move(LayoutUnit(), available_alignment_space); |
| |
| if (is_horizontal) |
| box->SetMarginTop(available_alignment_space); |
| else |
| box->SetMarginLeft(available_alignment_space); |
| return true; |
| } |
| if (bottom_or_right.IsAuto()) { |
| if (!should_adjust_top_or_left) |
| desired_location.Move(LayoutUnit(), available_alignment_space); |
| |
| if (is_horizontal) |
| box->SetMarginBottom(available_alignment_space); |
| else |
| box->SetMarginRight(available_alignment_space); |
| return true; |
| } |
| return false; |
| } |
| |
| void FlexItem::ComputeStretchedSize() { |
| DCHECK_EQ(Alignment(), ItemPosition::kStretch); |
| if (MainAxisIsInlineAxis() && box->StyleRef().LogicalHeight().IsAuto()) { |
| LayoutUnit stretched_logical_height = |
| std::max(box->BorderAndPaddingLogicalHeight(), |
| Line()->cross_axis_extent - CrossAxisMarginExtent()); |
| cross_axis_size = box->ConstrainLogicalHeightByMinMax( |
| stretched_logical_height, box->IntrinsicContentLogicalHeight()); |
| } else if (!MainAxisIsInlineAxis() && |
| box->StyleRef().LogicalWidth().IsAuto()) { |
| LayoutUnit child_width = |
| (Line()->cross_axis_extent - CrossAxisMarginExtent()) |
| .ClampNegativeToZero(); |
| if (LayoutFlexibleBox* flexbox = ToLayoutFlexibleBoxOrNull(box->Parent())) { |
| cross_axis_size = box->ConstrainLogicalWidthByMinMax( |
| child_width, flexbox->CrossAxisContentExtent(), flexbox); |
| } else { |
| DCHECK(box->Parent()->IsLayoutNGFlexibleBox()); |
| cross_axis_size = min_max_cross_sizes->ClampSizeToMinAndMax(child_width); |
| } |
| } |
| } |
| |
| // static |
| LayoutUnit FlexItem::AlignmentOffset(LayoutUnit available_free_space, |
| ItemPosition position, |
| LayoutUnit ascent, |
| LayoutUnit max_ascent, |
| bool is_wrap_reverse, |
| bool is_deprecated_webkit_box) { |
| switch (position) { |
| case ItemPosition::kLegacy: |
| case ItemPosition::kAuto: |
| case ItemPosition::kNormal: |
| NOTREACHED(); |
| break; |
| case ItemPosition::kStretch: |
| // Actual stretching must be handled by the caller. Since wrap-reverse |
| // flips cross start and cross end, stretch children should be aligned |
| // with the cross end. This matters because applyStretchAlignment |
| // doesn't always stretch or stretch fully (explicit cross size given, or |
| // stretching constrained by max-height/max-width). For flex-start and |
| // flex-end this is handled by alignmentForChild(). |
| if (is_wrap_reverse) |
| return available_free_space; |
| break; |
| case ItemPosition::kFlexStart: |
| break; |
| case ItemPosition::kFlexEnd: |
| return available_free_space; |
| case ItemPosition::kCenter: { |
| const LayoutUnit result = (available_free_space / 2); |
| return is_deprecated_webkit_box ? result.ClampNegativeToZero() : result; |
| } |
| case ItemPosition::kBaseline: |
| // FIXME: If we get here in columns, we want the use the descent, except |
| // we currently can't get the ascent/descent of orthogonal children. |
| // https://bugs.webkit.org/show_bug.cgi?id=98076 |
| return max_ascent - ascent; |
| case ItemPosition::kLastBaseline: |
| case ItemPosition::kSelfStart: |
| case ItemPosition::kSelfEnd: |
| case ItemPosition::kStart: |
| case ItemPosition::kEnd: |
| case ItemPosition::kLeft: |
| case ItemPosition::kRight: |
| // TODO(jferanndez): Implement these (https://crbug.com/722287). |
| break; |
| } |
| return LayoutUnit(); |
| } |
| void FlexLine::FreezeViolations(ViolationsVector& violations) { |
| const ComputedStyle& flex_box_style = algorithm->StyleRef(); |
| for (size_t i = 0; i < violations.size(); ++i) { |
| DCHECK(!violations[i]->frozen) << i; |
| LayoutBox* child = violations[i]->box; |
| LayoutUnit child_size = violations[i]->flexed_content_size; |
| remaining_free_space -= child_size - violations[i]->flex_base_content_size; |
| total_flex_grow -= child->StyleRef().ResolvedFlexGrow(flex_box_style); |
| const float flex_shrink = |
| child->StyleRef().ResolvedFlexShrink(flex_box_style); |
| total_flex_shrink -= flex_shrink; |
| total_weighted_flex_shrink -= |
| flex_shrink * violations[i]->flex_base_content_size; |
| // total_weighted_flex_shrink can be negative when we exceed the precision |
| // of a double when we initially calculate total_weighted_flex_shrink. We |
| // then subtract each child's weighted flex shrink with full precision, now |
| // leading to a negative result. See |
| // css3/flexbox/large-flex-shrink-assert.html |
| total_weighted_flex_shrink = std::max(total_weighted_flex_shrink, 0.0); |
| violations[i]->frozen = true; |
| } |
| } |
| |
| void FlexLine::FreezeInflexibleItems() { |
| // Per https://drafts.csswg.org/css-flexbox/#resolve-flexible-lengths step 2, |
| // we freeze all items with a flex factor of 0 as well as those with a min/max |
| // size violation. |
| FlexSign flex_sign = Sign(); |
| remaining_free_space = container_main_inner_size - sum_flex_base_size; |
| |
| ViolationsVector new_inflexible_items; |
| const ComputedStyle& flex_box_style = algorithm->StyleRef(); |
| for (size_t i = 0; i < line_items.size(); ++i) { |
| FlexItem& flex_item = line_items[i]; |
| LayoutBox* child = flex_item.box; |
| DCHECK(!flex_item.box->IsOutOfFlowPositioned()); |
| DCHECK(!flex_item.frozen) << i; |
| float flex_factor = |
| (flex_sign == kPositiveFlexibility) |
| ? child->StyleRef().ResolvedFlexGrow(flex_box_style) |
| : child->StyleRef().ResolvedFlexShrink(flex_box_style); |
| if (flex_factor == 0 || |
| (flex_sign == kPositiveFlexibility && |
| flex_item.flex_base_content_size > |
| flex_item.hypothetical_main_content_size) || |
| (flex_sign == kNegativeFlexibility && |
| flex_item.flex_base_content_size < |
| flex_item.hypothetical_main_content_size)) { |
| flex_item.flexed_content_size = flex_item.hypothetical_main_content_size; |
| new_inflexible_items.push_back(&flex_item); |
| } |
| } |
| FreezeViolations(new_inflexible_items); |
| initial_free_space = remaining_free_space; |
| } |
| |
| bool FlexLine::ResolveFlexibleLengths() { |
| LayoutUnit total_violation; |
| LayoutUnit used_free_space; |
| ViolationsVector min_violations; |
| ViolationsVector max_violations; |
| |
| FlexSign flex_sign = Sign(); |
| double sum_flex_factors = |
| (flex_sign == kPositiveFlexibility) ? total_flex_grow : total_flex_shrink; |
| if (sum_flex_factors > 0 && sum_flex_factors < 1) { |
| LayoutUnit fractional(initial_free_space * sum_flex_factors); |
| if (fractional.Abs() < remaining_free_space.Abs()) |
| remaining_free_space = fractional; |
| } |
| |
| const ComputedStyle& flex_box_style = algorithm->StyleRef(); |
| for (size_t i = 0; i < line_items.size(); ++i) { |
| FlexItem& flex_item = line_items[i]; |
| LayoutBox* child = flex_item.box; |
| |
| // This check also covers out-of-flow children. |
| if (flex_item.frozen) |
| continue; |
| |
| LayoutUnit child_size = flex_item.flex_base_content_size; |
| double extra_space = 0; |
| if (remaining_free_space > 0 && total_flex_grow > 0 && |
| flex_sign == kPositiveFlexibility && std::isfinite(total_flex_grow)) { |
| extra_space = remaining_free_space * |
| child->StyleRef().ResolvedFlexGrow(flex_box_style) / |
| total_flex_grow; |
| } else if (remaining_free_space < 0 && total_weighted_flex_shrink > 0 && |
| flex_sign == kNegativeFlexibility && |
| std::isfinite(total_weighted_flex_shrink) && |
| child->StyleRef().ResolvedFlexShrink(flex_box_style)) { |
| extra_space = remaining_free_space * |
| child->StyleRef().ResolvedFlexShrink(flex_box_style) * |
| flex_item.flex_base_content_size / |
| total_weighted_flex_shrink; |
| } |
| if (std::isfinite(extra_space)) |
| child_size += LayoutUnit::FromFloatRound(extra_space); |
| |
| LayoutUnit adjusted_child_size = flex_item.ClampSizeToMinAndMax(child_size); |
| DCHECK_GE(adjusted_child_size, 0); |
| flex_item.flexed_content_size = adjusted_child_size; |
| used_free_space += adjusted_child_size - flex_item.flex_base_content_size; |
| |
| LayoutUnit violation = adjusted_child_size - child_size; |
| if (violation > 0) |
| min_violations.push_back(&flex_item); |
| else if (violation < 0) |
| max_violations.push_back(&flex_item); |
| total_violation += violation; |
| } |
| |
| if (total_violation) { |
| FreezeViolations(total_violation < 0 ? max_violations : min_violations); |
| } else { |
| remaining_free_space -= used_free_space; |
| } |
| |
| return !total_violation; |
| } |
| |
| LayoutUnit FlexLine::ApplyMainAxisAutoMarginAdjustment() { |
| if (remaining_free_space <= LayoutUnit()) |
| return LayoutUnit(); |
| |
| int number_of_auto_margins = 0; |
| bool is_horizontal = algorithm->IsHorizontalFlow(); |
| for (size_t i = 0; i < line_items.size(); ++i) { |
| LayoutBox* child = line_items[i].box; |
| DCHECK(!child->IsOutOfFlowPositioned()); |
| if (is_horizontal) { |
| if (child->StyleRef().MarginLeft().IsAuto()) |
| ++number_of_auto_margins; |
| if (child->StyleRef().MarginRight().IsAuto()) |
| ++number_of_auto_margins; |
| } else { |
| if (child->StyleRef().MarginTop().IsAuto()) |
| ++number_of_auto_margins; |
| if (child->StyleRef().MarginBottom().IsAuto()) |
| ++number_of_auto_margins; |
| } |
| } |
| if (!number_of_auto_margins) |
| return LayoutUnit(); |
| |
| LayoutUnit size_of_auto_margin = |
| remaining_free_space / number_of_auto_margins; |
| remaining_free_space = LayoutUnit(); |
| return size_of_auto_margin; |
| } |
| |
| void FlexLine::ComputeLineItemsPosition(LayoutUnit main_axis_offset, |
| LayoutUnit& cross_axis_offset) { |
| this->main_axis_offset = main_axis_offset; |
| // Recalculate the remaining free space. The adjustment for flex factors |
| // between 0..1 means we can't just use remainingFreeSpace here. |
| remaining_free_space = container_main_inner_size; |
| for (size_t i = 0; i < line_items.size(); ++i) { |
| FlexItem& flex_item = line_items[i]; |
| DCHECK(!flex_item.box->IsOutOfFlowPositioned()); |
| remaining_free_space -= flex_item.FlexedMarginBoxSize(); |
| } |
| |
| const StyleContentAlignmentData justify_content = |
| FlexLayoutAlgorithm::ResolvedJustifyContent(*algorithm->Style()); |
| |
| LayoutUnit auto_margin_offset = ApplyMainAxisAutoMarginAdjustment(); |
| const LayoutUnit available_free_space = remaining_free_space; |
| LayoutUnit initial_position = |
| FlexLayoutAlgorithm::InitialContentPositionOffset( |
| available_free_space, justify_content, line_items.size()); |
| main_axis_offset += initial_position; |
| sum_justify_adjustments += initial_position; |
| LayoutUnit max_descent; // Used when align-items: baseline. |
| LayoutUnit max_child_cross_axis_extent; |
| bool should_flip_main_axis = |
| !algorithm->StyleRef().ResolvedIsColumnFlexDirection() && |
| !algorithm->IsLeftToRightFlow(); |
| for (size_t i = 0; i < line_items.size(); ++i) { |
| FlexItem& flex_item = line_items[i]; |
| |
| DCHECK(!flex_item.box->IsOutOfFlowPositioned()); |
| |
| flex_item.UpdateAutoMarginsInMainAxis(auto_margin_offset); |
| |
| LayoutUnit child_cross_axis_margin_box_extent; |
| if (flex_item.Alignment() == ItemPosition::kBaseline && |
| !flex_item.HasAutoMarginsInCrossAxis()) { |
| LayoutUnit ascent = flex_item.MarginBoxAscent(); |
| LayoutUnit descent = |
| (flex_item.CrossAxisMarginExtent() + flex_item.cross_axis_size) - |
| ascent; |
| |
| max_ascent = std::max(max_ascent, ascent); |
| max_descent = std::max(max_descent, descent); |
| |
| child_cross_axis_margin_box_extent = max_ascent + max_descent; |
| } else { |
| child_cross_axis_margin_box_extent = |
| flex_item.cross_axis_size + flex_item.CrossAxisMarginExtent(); |
| } |
| max_child_cross_axis_extent = std::max(max_child_cross_axis_extent, |
| child_cross_axis_margin_box_extent); |
| |
| main_axis_offset += flex_item.FlowAwareMarginStart(); |
| |
| LayoutUnit child_main_extent = flex_item.FlexedBorderBoxSize(); |
| // In an RTL column situation, this will apply the margin-right/margin-end |
| // on the left. This will be fixed later in |
| // LayoutFlexibleBox::FlipForRightToLeftColumn. |
| flex_item.desired_location = LayoutPoint( |
| should_flip_main_axis |
| ? container_logical_width - main_axis_offset - child_main_extent |
| : main_axis_offset, |
| cross_axis_offset + flex_item.FlowAwareMarginBefore()); |
| main_axis_offset += child_main_extent + flex_item.FlowAwareMarginEnd(); |
| |
| if (i != line_items.size() - 1) { |
| // The last item does not get extra space added. |
| LayoutUnit space_between = |
| FlexLayoutAlgorithm::ContentDistributionSpaceBetweenChildren( |
| available_free_space, justify_content, line_items.size()); |
| main_axis_offset += space_between; |
| sum_justify_adjustments += space_between; |
| } |
| } |
| |
| main_axis_extent = main_axis_offset; |
| |
| this->cross_axis_offset = cross_axis_offset; |
| cross_axis_extent = max_child_cross_axis_extent; |
| |
| cross_axis_offset += max_child_cross_axis_extent; |
| } |
| |
| FlexLayoutAlgorithm::FlexLayoutAlgorithm(const ComputedStyle* style, |
| LayoutUnit line_break_length) |
| : style_(style), |
| line_break_length_(line_break_length), |
| next_item_index_(0) {} |
| |
| FlexLine* FlexLayoutAlgorithm::ComputeNextFlexLine( |
| LayoutUnit container_logical_width) { |
| LayoutUnit sum_flex_base_size; |
| double total_flex_grow = 0; |
| double total_flex_shrink = 0; |
| double total_weighted_flex_shrink = 0; |
| LayoutUnit sum_hypothetical_main_size; |
| |
| bool line_has_in_flow_item = false; |
| |
| wtf_size_t start_index = next_item_index_; |
| |
| for (; next_item_index_ < all_items_.size(); ++next_item_index_) { |
| FlexItem& flex_item = all_items_[next_item_index_]; |
| DCHECK(!flex_item.box->IsOutOfFlowPositioned()); |
| if (IsMultiline() && |
| sum_hypothetical_main_size + |
| flex_item.HypotheticalMainAxisMarginBoxSize() > |
| line_break_length_ && |
| line_has_in_flow_item) { |
| break; |
| } |
| line_has_in_flow_item = true; |
| sum_flex_base_size += flex_item.FlexBaseMarginBoxSize(); |
| total_flex_grow += flex_item.box->StyleRef().ResolvedFlexGrow(StyleRef()); |
| const float flex_shrink = |
| flex_item.box->StyleRef().ResolvedFlexShrink(StyleRef()); |
| total_flex_shrink += flex_shrink; |
| total_weighted_flex_shrink += |
| flex_shrink * flex_item.flex_base_content_size; |
| sum_hypothetical_main_size += flex_item.HypotheticalMainAxisMarginBoxSize(); |
| flex_item.line_number = flex_lines_.size(); |
| } |
| |
| DCHECK(next_item_index_ > start_index || |
| next_item_index_ == all_items_.size()); |
| if (next_item_index_ > start_index) { |
| return &flex_lines_.emplace_back( |
| this, FlexItemVectorView(&all_items_, start_index, next_item_index_), |
| container_logical_width, sum_flex_base_size, total_flex_grow, |
| total_flex_shrink, total_weighted_flex_shrink, |
| sum_hypothetical_main_size); |
| } |
| return nullptr; |
| } |
| |
| bool FlexLayoutAlgorithm::IsHorizontalFlow() const { |
| return IsHorizontalFlow(*style_); |
| } |
| |
| bool FlexLayoutAlgorithm::IsColumnFlow() const { |
| return StyleRef().ResolvedIsColumnFlexDirection(); |
| } |
| |
| // static |
| bool FlexLayoutAlgorithm::IsHorizontalFlow(const ComputedStyle& style) { |
| if (style.IsHorizontalWritingMode()) |
| return !style.ResolvedIsColumnFlexDirection(); |
| return style.ResolvedIsColumnFlexDirection(); |
| } |
| |
| bool FlexLayoutAlgorithm::IsLeftToRightFlow() const { |
| if (style_->ResolvedIsColumnFlexDirection()) { |
| return blink::IsHorizontalWritingMode(style_->GetWritingMode()) || |
| IsFlippedLinesWritingMode(style_->GetWritingMode()); |
| } |
| return style_->IsLeftToRightDirection() ^ |
| style_->ResolvedIsRowReverseFlexDirection(); |
| } |
| |
| // static |
| const StyleContentAlignmentData& |
| FlexLayoutAlgorithm::ContentAlignmentNormalBehavior() { |
| // The justify-content property applies along the main axis, but since |
| // flexing in the main axis is controlled by flex, stretch behaves as |
| // flex-start (ignoring the specified fallback alignment, if any). |
| // https://drafts.csswg.org/css-align/#distribution-flex |
| static const StyleContentAlignmentData kNormalBehavior = { |
| ContentPosition::kNormal, ContentDistributionType::kStretch}; |
| return kNormalBehavior; |
| } |
| |
| bool FlexLayoutAlgorithm::ShouldApplyMinSizeAutoForChild( |
| const LayoutBox& child) const { |
| // css-flexbox section 4.5 |
| const Length& min = IsHorizontalFlow() ? child.StyleRef().MinWidth() |
| : child.StyleRef().MinHeight(); |
| if (!min.IsAuto()) |
| return false; |
| |
| // webkit-box treats min-size: auto as 0. |
| if (StyleRef().Display() == EDisplay::kWebkitBox || |
| StyleRef().Display() == EDisplay::kWebkitInlineBox) { |
| return false; |
| } |
| |
| return !child.ShouldApplySizeContainment() && |
| MainAxisOverflowForChild(child) == EOverflow::kVisible; |
| } |
| |
| LayoutUnit FlexLayoutAlgorithm::IntrinsicContentBlockSize() const { |
| if (flex_lines_.IsEmpty()) |
| return LayoutUnit(); |
| |
| if (IsColumnFlow()) { |
| LayoutUnit max_size; |
| for (const FlexLine& line : flex_lines_) { |
| // Subtract main_axis_offset to remove border/padding |
| max_size = std::max(line.main_axis_extent - line.sum_justify_adjustments - |
| line.main_axis_offset, |
| max_size); |
| } |
| return max_size; |
| } |
| |
| const FlexLine& last_line = flex_lines_.back(); |
| // Subtract the first line's offset to remove border/padding |
| return last_line.cross_axis_offset + last_line.cross_axis_extent - |
| flex_lines_.front().cross_axis_offset; |
| } |
| |
| void FlexLayoutAlgorithm::AlignFlexLines(LayoutUnit cross_axis_content_extent) { |
| const StyleContentAlignmentData align_content = ResolvedAlignContent(*style_); |
| if (align_content.GetPosition() == ContentPosition::kFlexStart) |
| return; |
| if (flex_lines_.IsEmpty() || !IsMultiline()) |
| return; |
| LayoutUnit available_cross_axis_space = cross_axis_content_extent; |
| for (const FlexLine& line : flex_lines_) |
| available_cross_axis_space -= line.cross_axis_extent; |
| |
| LayoutUnit line_offset = InitialContentPositionOffset( |
| available_cross_axis_space, align_content, flex_lines_.size()); |
| for (FlexLine& line_context : flex_lines_) { |
| line_context.cross_axis_offset += line_offset; |
| |
| for (FlexItem& flex_item : line_context.line_items) { |
| flex_item.desired_location.SetY(flex_item.desired_location.Y() + |
| line_offset); |
| } |
| if (align_content.Distribution() == ContentDistributionType::kStretch && |
| available_cross_axis_space > 0) { |
| line_context.cross_axis_extent += |
| available_cross_axis_space / |
| static_cast<unsigned>(flex_lines_.size()); |
| } |
| |
| line_offset += ContentDistributionSpaceBetweenChildren( |
| available_cross_axis_space, align_content, flex_lines_.size()); |
| } |
| } |
| |
| void FlexLayoutAlgorithm::AlignChildren() { |
| // Keep track of the space between the baseline edge and the after edge of |
| // the box for each line. |
| Vector<LayoutUnit> min_margin_after_baselines; |
| |
| for (FlexLine& line_context : flex_lines_) { |
| LayoutUnit min_margin_after_baseline = LayoutUnit::Max(); |
| LayoutUnit max_ascent = line_context.max_ascent; |
| |
| for (FlexItem& flex_item : line_context.line_items) { |
| DCHECK(!flex_item.box->IsOutOfFlowPositioned()); |
| |
| if (flex_item.UpdateAutoMarginsInCrossAxis( |
| std::max(LayoutUnit(), flex_item.AvailableAlignmentSpace()))) { |
| continue; |
| } |
| |
| ItemPosition position = flex_item.Alignment(); |
| if (position == ItemPosition::kStretch) |
| flex_item.ComputeStretchedSize(); |
| LayoutUnit available_space = flex_item.AvailableAlignmentSpace(); |
| LayoutUnit offset = FlexItem::AlignmentOffset( |
| available_space, position, flex_item.MarginBoxAscent(), max_ascent, |
| StyleRef().FlexWrap() == EFlexWrap::kWrapReverse, |
| StyleRef().IsDeprecatedWebkitBox()); |
| flex_item.desired_location.Move(LayoutUnit(), offset); |
| if (position == ItemPosition::kBaseline && |
| StyleRef().FlexWrap() == EFlexWrap::kWrapReverse) { |
| min_margin_after_baseline = |
| std::min(min_margin_after_baseline, |
| flex_item.AvailableAlignmentSpace() - offset); |
| } |
| } |
| min_margin_after_baselines.push_back(min_margin_after_baseline); |
| } |
| |
| if (StyleRef().FlexWrap() != EFlexWrap::kWrapReverse) |
| return; |
| |
| // wrap-reverse flips the cross axis start and end. For baseline alignment, |
| // this means we need to align the after edge of baseline elements with the |
| // after edge of the flex line. |
| wtf_size_t line_number = 0; |
| for (FlexLine& line_context : flex_lines_) { |
| LayoutUnit min_margin_after_baseline = |
| min_margin_after_baselines[line_number++]; |
| for (FlexItem& flex_item : line_context.line_items) { |
| if (flex_item.Alignment() == ItemPosition::kBaseline && |
| !flex_item.HasAutoMarginsInCrossAxis() && min_margin_after_baseline) { |
| flex_item.desired_location.Move(LayoutUnit(), |
| min_margin_after_baseline); |
| } |
| } |
| } |
| } |
| |
| void FlexLayoutAlgorithm::FlipForWrapReverse( |
| LayoutUnit cross_axis_start_edge, |
| LayoutUnit cross_axis_content_size) { |
| DCHECK_EQ(Style()->FlexWrap(), EFlexWrap::kWrapReverse); |
| for (FlexLine& line_context : flex_lines_) { |
| LayoutUnit original_offset = |
| line_context.cross_axis_offset - cross_axis_start_edge; |
| LayoutUnit new_offset = cross_axis_content_size - original_offset - |
| line_context.cross_axis_extent; |
| LayoutUnit wrap_reverse_difference = new_offset - original_offset; |
| for (FlexItem& flex_item : line_context.line_items) |
| flex_item.desired_location.Move(LayoutUnit(), wrap_reverse_difference); |
| } |
| } |
| |
| TransformedWritingMode FlexLayoutAlgorithm::GetTransformedWritingMode() const { |
| return GetTransformedWritingMode(*style_); |
| } |
| |
| // static |
| TransformedWritingMode FlexLayoutAlgorithm::GetTransformedWritingMode( |
| const ComputedStyle& style) { |
| WritingMode mode = style.GetWritingMode(); |
| if (!style.ResolvedIsColumnFlexDirection()) { |
| static_assert( |
| static_cast<TransformedWritingMode>(WritingMode::kHorizontalTb) == |
| TransformedWritingMode::kTopToBottomWritingMode && |
| static_cast<TransformedWritingMode>(WritingMode::kVerticalLr) == |
| TransformedWritingMode::kLeftToRightWritingMode && |
| static_cast<TransformedWritingMode>(WritingMode::kVerticalRl) == |
| TransformedWritingMode::kRightToLeftWritingMode, |
| "WritingMode and TransformedWritingMode must match values."); |
| return static_cast<TransformedWritingMode>(mode); |
| } |
| |
| switch (mode) { |
| case WritingMode::kHorizontalTb: |
| return style.IsLeftToRightDirection() |
| ? TransformedWritingMode::kLeftToRightWritingMode |
| : TransformedWritingMode::kRightToLeftWritingMode; |
| case WritingMode::kVerticalLr: |
| case WritingMode::kVerticalRl: |
| return style.IsLeftToRightDirection() |
| ? TransformedWritingMode::kTopToBottomWritingMode |
| : TransformedWritingMode::kBottomToTopWritingMode; |
| // TODO(layout-dev): Sideways-lr and sideways-rl are not yet supported. |
| default: |
| break; |
| } |
| NOTREACHED(); |
| return TransformedWritingMode::kTopToBottomWritingMode; |
| } |
| |
| // static |
| StyleContentAlignmentData FlexLayoutAlgorithm::ResolvedJustifyContent( |
| const ComputedStyle& style) { |
| const bool is_webkit_box = style.IsDeprecatedWebkitBox(); |
| ContentPosition position = is_webkit_box |
| ? BoxPackToContentPosition(style.BoxPack()) |
| : style.ResolvedJustifyContentPosition( |
| ContentAlignmentNormalBehavior()); |
| ContentDistributionType distribution = |
| is_webkit_box ? BoxPackToContentDistribution(style.BoxPack()) |
| : style.ResolvedJustifyContentDistribution( |
| ContentAlignmentNormalBehavior()); |
| OverflowAlignment overflow = style.JustifyContentOverflowAlignment(); |
| // For flex, justify-content: stretch behaves as flex-start: |
| // https://drafts.csswg.org/css-align/#distribution-flex |
| if (!is_webkit_box && distribution == ContentDistributionType::kStretch) { |
| position = ContentPosition::kFlexStart; |
| distribution = ContentDistributionType::kDefault; |
| } |
| return StyleContentAlignmentData(position, distribution, overflow); |
| } |
| |
| // static |
| StyleContentAlignmentData FlexLayoutAlgorithm::ResolvedAlignContent( |
| const ComputedStyle& style) { |
| ContentPosition position = |
| style.ResolvedAlignContentPosition(ContentAlignmentNormalBehavior()); |
| ContentDistributionType distribution = |
| style.ResolvedAlignContentDistribution(ContentAlignmentNormalBehavior()); |
| OverflowAlignment overflow = style.AlignContentOverflowAlignment(); |
| return StyleContentAlignmentData(position, distribution, overflow); |
| } |
| |
| // static |
| ItemPosition FlexLayoutAlgorithm::AlignmentForChild( |
| const ComputedStyle& flexbox_style, |
| const ComputedStyle& child_style) { |
| ItemPosition align = |
| flexbox_style.IsDeprecatedWebkitBox() |
| ? BoxAlignmentToItemPosition(flexbox_style.BoxAlign()) |
| : child_style |
| .ResolvedAlignSelf(ItemPosition::kStretch, &flexbox_style) |
| .GetPosition(); |
| DCHECK_NE(align, ItemPosition::kAuto); |
| DCHECK_NE(align, ItemPosition::kNormal); |
| |
| if (align == ItemPosition::kBaseline && |
| IsHorizontalFlow(flexbox_style) != child_style.IsHorizontalWritingMode()) |
| align = ItemPosition::kFlexStart; |
| |
| if (flexbox_style.FlexWrap() == EFlexWrap::kWrapReverse) { |
| if (align == ItemPosition::kFlexStart) |
| align = ItemPosition::kFlexEnd; |
| else if (align == ItemPosition::kFlexEnd) |
| align = ItemPosition::kFlexStart; |
| } |
| |
| return align; |
| } |
| |
| // static |
| LayoutUnit FlexLayoutAlgorithm::InitialContentPositionOffset( |
| LayoutUnit available_free_space, |
| const StyleContentAlignmentData& data, |
| unsigned number_of_items) { |
| if (data.GetPosition() == ContentPosition::kFlexEnd) |
| return available_free_space; |
| if (data.GetPosition() == ContentPosition::kCenter) |
| return available_free_space / 2; |
| if (data.Distribution() == ContentDistributionType::kSpaceAround) { |
| if (available_free_space > 0 && number_of_items) |
| return available_free_space / (2 * number_of_items); |
| |
| return available_free_space / 2; |
| } |
| if (data.Distribution() == ContentDistributionType::kSpaceEvenly) { |
| if (available_free_space > 0 && number_of_items) |
| return available_free_space / (number_of_items + 1); |
| // Fallback to 'center' |
| return available_free_space / 2; |
| } |
| return LayoutUnit(); |
| } |
| |
| // static |
| LayoutUnit FlexLayoutAlgorithm::ContentDistributionSpaceBetweenChildren( |
| LayoutUnit available_free_space, |
| const StyleContentAlignmentData& data, |
| unsigned number_of_items) { |
| if (available_free_space > 0 && number_of_items > 1) { |
| if (data.Distribution() == ContentDistributionType::kSpaceBetween) |
| return available_free_space / (number_of_items - 1); |
| if (data.Distribution() == ContentDistributionType::kSpaceAround || |
| data.Distribution() == ContentDistributionType::kStretch) |
| return available_free_space / number_of_items; |
| if (data.Distribution() == ContentDistributionType::kSpaceEvenly) |
| return available_free_space / (number_of_items + 1); |
| } |
| return LayoutUnit(); |
| } |
| |
| EOverflow FlexLayoutAlgorithm::MainAxisOverflowForChild( |
| const LayoutBox& child) const { |
| if (IsHorizontalFlow()) |
| return child.StyleRef().OverflowX(); |
| return child.StyleRef().OverflowY(); |
| } |
| |
| } // namespace blink |
